The use of computer-controlled robots is becoming increasingly widespread in industry. Once their initial purchase cost has been amortized, experience has shown that robots are less expensive to operate, and considerably more reliable, than the human operators they replace, especially in repetitive assembly applications where human judgement is not a critical factor.
A typical robot arm will comprise three or more arm sections operatively coupled by computer controlled joints which may be analogized, for example, to the human shoulder, elbow and wrist joints. A "hand" is typically attached to the extremity of the arm to manipulate the workpiece, as required by the particular task to be performed.
For such an arm to be useful it is, of course, necessary to be able to move the arm so that the "hand" can pick up, manipulate, and then set down the workpiece. Typically, this is accomplished by noting the coordinates of the beginning and end positions of the hand and then computing the precise angle through which each joint must be rotated so that the hand reaches the desired end position.
In such an arrangement, the ultimate position of the hand depends not only on the degree of rotation of the "wrist" joint, but also on the degree of rotation of all other joints upstream of the wrist joint. Because of this interdependence, computation of the changes necessary in the various joint angles of the arm becomes exceedingly complex. In addition, because of the computational precision necessary, the time to complete the computation is relatively long, especially if an 8-bit microprocessor is used to perform the calculations.